Suppose you're developing an independent, small sub-page for a big and well frequented web portal.
The sub-page shows entries from a public event calendar, and allows users to highlight those especially interesting to them. The highlighted events shall be highlighted (and maybe shown on a separate list) on each future visit of that user.
However, building a classical user registration system, or any other way of storing the user-highlighted event picks on the server, is not an option: The sub-module needs to be as self-contained and need as little maintenance as possible. It's one of the conditions of the project.
The only way to do this without building a login system of some sort (as far as I can see) is using cookies or some other local storage (Flash / HTML 5....) which has the obvious and big downside that it's tied to the computer, not the user.
Is there a way of storing a few kilobytes data on a per-person basis, but without having to utilize a login or openID, that I am overlooking? A reliable web service perhaps?
A "key/value" storage service, to which I pass a unique key (one that the user specified) and get the savedvalue in return, would be sufficient. There is no need for real security - the data in question is by no means confidential.
OpenID is not an option: It is not well known enough among the audience of the site.
Facebook would be an option, but I don't think they provide "storage" options like this.
As a workaround, I am contemplating offering the user their event picks as a text file download, that also can be uploaded and turned into cookies on another machine. But that is pretty complicated for the user, and thus not perfect.